Automatically controlled switch



July 24, 192.8. 1,678,507

G. H. HART AUTOMATICALLY CONTROLLED SWITCH Filed Nov. 20, 1924 imam 1| Em KKK Patented July 24, 1928.

' UNITED STATES PATENT OFFICE GEORGE HEGEMAN HART, OF WEST HARTFORD, CONNEGTICUT, AUTOMATICALLY CONTROLLED SWTTGH.

Application filed November 20, 1924. Serial Ito/751,049.

This invention relates generally to electric switches, for example, switches which are automatically controlled, for instance thermostatically, and have covers by means of which the switches may be set or ad usted, end of this screw protrudes into the opening in which the covers are connected to the base or supporting body.

Anobject of the invention is to provide improved means having various features of novelty and advantage for holding the cap or cover of the switch in place and for rotary adjustment.

more specific aim of the invention is to provide an improved arrangement by means of which the cover may be very quickly and readily assembled on the base and removed therefrom.

A further object is to provide means for holding the cover in place which is very simple and economical in construction and eflicient in operation.

A still further aim is to provide means cts for holding the cap or cover in place without the use of screws or similar securing means; the securing means in the present disclosure being entirely concealed from view by the cover.

Another object is to provide a construction which will permit the cover to be readily removed and replaced without impairing the setting or adjustment of the switch which it houses.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention, accordingly, consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and thescope of the application of which will be indicated in the appended claims.

In the accompanying drawings, wherein I have shown, for illustrative purposes, one embodiment which the present invention may take:

Figure 1 is a view of controlled electric switch cap thereof in section;

Fig. 2 is a horizontal sectional view taken substantially on line 2-2 of Fig. 1, with the cover turned counterclockwise through an angle of substantially 90 degrees;

Fig. 3 is a sectional view taken substantially on line 3-3 of Fig. 2, but with the a thermostatically with the cover or cover raised slightly from the position which it occupies in Fig. 2;

Fig. 4 is a detail view of that side of the base of the switch diametrically opposite to that observed in Fig. l; and Fig. 5 is a plan view of what is illustrated in Fig. 4, and shows, additionally, the relat1o n of the cover to the base when the cover 1s m gpsition to be removed.

In 1g. 1 of the accompanying drawings,

have shown the features of the present invention applied to a thermostatically controlled switch similar to that disclosed in the application for U. S. Letters Patent of Gerald W. Hart, Serial No. 675,092, filed November 16, 1923, but it is to be understood that the present disclosure is by way of illustration only and that m invention is not limited in use to the speci c embodiment here illustrated.

Referring to the drawings in detail, the electric switch proper includes a pair of conand 11, and a switch arm 12 having, in its free end, an insulated circuit closing member or pin 13 positioned between the contacts 10 and 11. The other end of the switch arm is pivoted in a lug or bracket 14. The terminals 10 and 11 and .the bracket 14 are mounted on a plate 15 of insulating material located within a base 16 of suitable construction. The circuit closing member 13 is normally urged towards the terminal 10 by a leaf spring 18 which also serves as a conducting member, as explained more in detail in the said Gerald W. Hart application. The respective terminals 10 and 11 are adapted to be connected to lead wires (not shown).

The switch is automatically operated by a suitable responsive device, such, for instance, as a thermostat, which may include a tube 20 having a relatively high co-efiicient of expansion and a rod 21 within the tube and having a relatively low co-eflicient of expansion. The tube may be connected to the base 16. The switch is associated with the thermostatic device by means of a plunger 22 having a head 23 normally urged against the upper end of the rod 21 by a spring 24. The plunger extends upwardly through the plate of insulating material 15 and a bracket 26. Cooperating with the switch arm 12 is a lever 28 pivoted'as at 29 and extending through a transverse opening 30 in the upper end of the plunger. For the purpose of varying the effective length of the plunger,

.and thereby adjusting the device to operate at any predetermined temperature, .there is provided in the upper end of the plunger an adjustable member which is shown as being in the form of a screw 31. The lower end of this screw protrudes mto the opening 30 and engages the upper edge of the lever 28. The screw is preliminaril ad usted within the plunger to determine t e range of temperature within which the thermostatic device will actuate the switch. In order to set or' regulate this screw so .that the thermostatic devlce will actuate the switch at any desired predetermined temperature within the selected range, the screw is connected to a rotatable cover 32 which carries one element of the temperature indicating means. This element, in the present instance,takes the form of a scale cooperating with an mdicating mark or pointer 33 on the base. The scale may be provided on a sheet of metal 34 which closely surroundsthe cyllndrical portion of the cover and 1S suitably secured thereto. The cover may be ad ustably connected in any suitable manner to the screw 31 as, for example, by means of a lug 35 engaging in .the kerf of sa1d screw, The arrangement so far described is similar to that illustrated in said Gerald Hart application.

Referring now present invention,

to the improvements of the the base 16 has a cylindrical portion about which the lower or open end of .the cover fits, and this cylindrical ortion has a circumferential groove 38 in which is adapted to engage one or more projections orlugs on the cover. In the present instance, two such lugs 39 and 40, diametrically positioned, are provided. These lugs may be formed in any suitable manner but, for the sake of simpliclty, and to eifect economy in manufacture, they are made by indenting the wall of the cover. By grooving the cylindrical P01131011 of the base, as at 38, there is provided a circumferential rib 41, against the underface of which the lugs 39 and 40 engage when the cover is in position. The edge of the cover abuts against the shoulder or flange 42. To permit the cover to be assembled onto, and dissembled from, the base, the rib 41 1s notched at diametrically opposite points, as at 43 and 44. These notches may be cons'idered as constituting grooves leading into .the circumferential groove 38.

For the purpose of preventing the coverfrom being accidentally or inadvertently removed from the base, one of the notches, in the present instance the notch 43, is normally obstructed or interrupted by a stop 46 which is preferably in the form of a plunger pressed outwardly by a spring 47. The projecting' end of the stop is rounded or crowned, as shown, and, preferably, the lug 39, which'is adapted to cooperate with this stop, is also domed or rounded so that, when sufiicient force is ap lied, the lug 39 will cam the plunger bac whereupon the lug may be moved through the notch or groove 43. In order that the lugs 39 and 40 may be respectively brought into registry with the grooves or notches 43 and 44, when it is desired to remove the cover, there is provided, within the groove 38, a stop 48 having a shoulder 49 in alinement with one edge of the notch 44, as shown most clearly in Figs. 4 and 5.

The operation of the device is briefly as follows: When it is desired to remove the cover from the base, the formeris turned, in the present instance, counterclockwise, whereupon the lug 39 is brought into engagement with the retractible stop or plunger 46, with the result that the latter is cammed inwardly to .the position shown in Fig. 2, thus permitting the lugs 39 and 40 to be brought into registry with the grooves 43 and 44, respectively. The stop! 48 serves to limit rotary movement of t e cover or cap to the position shown in Fig. 2. The cover may now be slipped from place. When it is desired to assemble the cover onto the base, it is merely necessary to bring the lugs into registry with the notches and then force the cover downwardly, whereupon the lug 39 cams the plunger 46 inwardly, and then the cover may be rotated to engage the lugs beneath the rib 41 and to set or regulate the screw 31 so that the thermostatic device will actuate the switch at any desired tempera- I ture within the selected range.

From the foregoing descrlption, it will .be seen that the means for securing the. cover to the base is very simple and economical in construction. The use of screws or the like is eliminated, and the securing or holding means is entirely concealed. The cover cannot become accidently removed from the base, while, at the same time, it may be deliberately removed and replaced very readily and quickly. The cover may be removed and replaced without disturbing the adjusted relation of the screw 31 to the plunger.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense; for instance, the retractible stop may have a form other than a spring pressed plunger and, instead of being cammed out of the way by the cover, it may be retracted by a separate instrument.

It is also to be understood that the lanage used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention:

1. In a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a notch entering thereinto, a rotary cover having a skirt portion, encircling sald cylin drical portion and provided with a lug adapted to enter said notch and engage n said groove, and resilient means 111 sa d groove and against which said lug is adapted to engage for preventing accidental removal of the cover from said body, said lug being movable in said groove to permit angular adjustment of said cover, and said resilient means engaging said cover and acting as a drag thereon to hold the cover in any desired position of adjustment.

2. In a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a notch entering thereinto, a rotary cover having a skirt portion encircling said cylin= drical portion and provided with a lug adapted to enter said notch and engage in said groove, and a spring pressed member projecting into said groove at said notch for preventing said lug from freely registering with said notch, said lug being movable in said groove to permit angular adjustment of said cover, and said resilient means engaging said cover and acting as a drag thereon to hold the cover in any desired position of adjustment.

3. In a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a notch entering thereinto, a rotary cover having a skirt portion encircling said cylindrical ortion and provided with a lug adapte to enter said notch and engage in said groove, and resilient means in said groove and against which said lug is adapted to engage for preventing accidental removal of the cover from said body, said lug and resilient means having co-acting cam surfaces whereby said lug may cam said means out of the path of the lug.

4. In a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a notch entering thereinto, a rotary cover having a skirt portion encircling said cylin drical portion and provided with a lug adapted to enter said notch and engage in said groove, and a spring pressed member projecting into said groove at said notch for preventing said lug from freelyregistering with said notch, said lug and member having rounded surfaces adapted to engage, whereby said lug may cam said member out of thei way when it is desired to remove the cover from the body.

5. In a device of the character described, a body having a cylindrical portion provided with a rib, a rotary cover having a skirt portion encircling said cylindrical portion and provided with a lug adapted to engage behind said rib, said rib having a notch' through which said lug may pass, and a spring pressed plunger carried by said body portion and normally obstructing said notch said lug being formed by indenting the metal of said cover and having a rounded surface adapted to engage said plunger to retract the same when it is desired-to assemble the $0581 on, and dissemble the same from, said 6. In a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a notch entering thereinto, a rotar cover having a skirt portion encircling sai cylindrical portion and provided with a lug adapted to enter said notch and engage in said ove, a spring pressed member projecting into said groove at said notch for preventing said lug from freely registering with said notch, and means for limiting the rotary movement of said cover relative to said body to a position where said lug registers with said notch. 7. In a device of the character described, a body having a cylindrical portion, a rotary cover having a skirt portion encircling said cylindrical portion, one of said portions being provided with a rib and the other of said portions having a pair of lugs adapted to engage behind said rib, said rib having a pair of notches through which the respective lugs may pass when assembling the cover on, and dissembling it from, said body means associated with one of said notches for preventing the lugs from freely registering therewith, and means for limiting rotary movement of said cover relative to said body to a position where said lugs register, with said notches.

8. In a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a pair of notches entering thereinto, a rotary cover having a skirt portion encircling said cylindrical ortion and provided with a pair of lugs a apted to enter the respective notches and engage in said groove, a spring pressed member projectin into said groove at one of said notches Ior preventing said lugs from freely registering with said notches, and means associated with the other of said notches for limitingrotary movement of said cover relative to said body to a position where said lugs register with said notches.

9. In' a device of the character described, a body having a cylindrical portion provided with a circumferential groove and a pair of notches entering thereinto, a rotary cover having a skirt portion encircling said cylinand in combination, a base having a cylin- 15 drical portion and provided with a pair of drical portion, ,an automatically operated lugs adapted to enter the respective notches switch within said base, a cover associated and engage in said groove, :1 spring pressed with said switch for regulating the same, plunger projecting into said groove adjacent said cover having a skirt portion encircling one of said notches for preventing said lugs said cylindrical portion of said base, said 20 from freely registering with said notches, cylindrical portion having a circumferential said member and the lug adapted to cogroove and a notch entering thereinto,-said operate therewith having rounded surfaces skirt portlon having :1. lug adapted to enter 1 whereby said lug may earn said member out said notch and engage 1n said groove, and of the way, and a shoulder in said groove spring pressed means projecting into said 25 adjacent said other notch and against which groove for preventin said lug from registhe other of said lugs is adapted to engage. termg with said note 10. In a device of the character described, GEORGE HEGEMAN HART. 

